Palisades Nuclear Power Plant will remain closed until 'early summer' to replace bottom of leaking tank

KALAMAZOO, MI -- For nuclear power plants, the question of whether to replace vs. repair isn't as simple a call as, say, buying a new car after the old one wears out, an independent nuclear safety expert explained.

The repairs are likely to keep the Covert Township facility, which is owned by New Orleans-based Entergy Corp. offline until at least early summer, said Lindsay Rose, spokeswoman for Palisades in an email.

While some Southwest Michigan residents and antinuclear activists had called for a complete replacement of the tank, David Lochbaum, director of the Union of
Concerned Scientists' nuclear safety project, said that replacement vs.
repair "is not a black and white call."

Stressing
that he had no specific, firsthand knowledge of the condition of
Palisades' SIRW tank, Lochbaum explained in an email that the failure
rate is highest at both the beginning and end of a product's lifespan.

"The
high failure rate is attributed to factors such as bad materials,
imperfect assemble, and user error that allow new products to fail," he
wrote.

On the other end of the lifespan are factors such as
embrittlement, rusting, etc.

Lochbaum cited as a
recent example the San Onofre nuclear plant in California, whose owner
paid $780 million to replace two aging steam generators on each of two reactors
-- one of which failed in January 2012, less than a year after
installation. Workers found significant degradation on all of the
replacement steam generators, caused by unexpected vibration.

Both reactors are still shut down and a restart date has not yet been set, said Lochbaum.

"Thus,
Entergy's choice on the SIRWT is to either repair an aging component
that is heading towards if not already within the wearout zone or to
replace it with a brand spanking new tank that inherently has a
relatively high chance of failure, too," wrote Lochbaum.

The NRC has said that, while the unplanned release never should have occurred, the incident did not represent a threat to the public's health
or safety.

"NRC inspectors are following the
plant's examinations and are in communication with the plant on their proposed
repair methodology," said Viktoria Mitlyng, spokeswoman for the NRC, in an email Tuesday. "The NRC will
ensure the repairs comply with regulations, and we will make sure they
are implemented safely and the plant can operate safely.

"At the same time," Mitlyng added, "we
are evaluating the plant's handling of this issue."

When asked about whether the replacement of the bottom of the tank represented the "permanent solution" he called for before Palisades could return to service, U.S. Rep. Fred Upton, R-St. Joseph, said that needed to be the NRC's call.

"Look, the bottom line is the NRC has to have all the tools to do things right," said Upton in a statement. "This should never be political. But we need to ensure the operational safety of every facility."

This the second time within a year that Palisades has shut down to deal with a leak in the SIRW tank, which is used during emergencies and for refueling. The tank is original to the plant, which began service in 1971.

Last June, Palisades shut down for 30 days to repair a leak in the tank. When it returned to service in July, the tank, which holds up to 300,000 gallons, still had a small leak, but the NRC said it could return to service as long as the leak was monitored and the amount remained below an agreed-upon 38 gallon-per-day threshold.

When the leak accelerated from about 1 gallon per day to about 90 gallons within a 24-hour period earlier this month, Palisades, as agreed, shut down.

Lochbaum said that the NRC's confirmatory action letter acts as a protection to the public.

"As happened recently, the owner must shut down the reactor when tank leakage exceeds a relatively modest amount," wrote Lochbaum. "Patch or purchase, this limit provides protection against an inadequate fix."

Yvonne Zipp is a reporter for the Kalamazoo Gazette, a part of the MLive Media Group. You can reach her at yzipp@mlive.com or 269-365-8639.